The invention relates to tamper-indicating closures and their use with containers.
Plastic closures have been used which provide a tamper band portion affixed to the lower free edge of the closure skirt by weakened means integral with the closure which cause the band to be severed from the closure skirt when the applied closure is unscrewed or lifted on the container neck finish. The container is provided with screw threads on its neck finish adjacent the container opening and below the thread portion is an annular external ring or bead. In some prior closures of this type the band includes flexible portions, such as wings, along its inner surface which deflect over the container bead until they are beneath it. The deflection arises in on-screwing the closure, however, unscrewing the closure results in engagement with the bead without deflection causing the band to be severed from the remainder of the closure and this severance indicates that the closure has been initially opened. Examples of such tamper-indicating closures found in the prior art disclosed by U.S. Pat. Nos. 4,497,765, 4,520,939 and 4,592,476. To close the mouth at the neck of the container, the threads of the closure travel over the threads of the neck finish in the onscrewing rotation. The flexible portions are angled such that they ride over the container bead and move below it to the closed position on the container. Upon rotation in the unscrewing direction, the flexible portions extend inwardly and do not deflect over the finish bead so that the upward movement of the band is intefered with by the flexible portion. The tamper band cannot move upwardly with the closure and the stress created by the interference breaking the band from the skirt.
The angled flexible wings may be defeated from their normal function by inserting a thin member, such as shim stock or the like, between the band and the container and manipulating the wings in the opposite direction. Thereafter, unscrewing the closure produces the reaction normally obtained in onscrewing the closure in which the wings deflect over the annular bead on the container without the tamper band being broken away. Thus the guarantee of the package against tampering is defeated.
The application of closures on a container finish in which the lowermost tamper band has inwardly extending projections on the inside surface requires top loading the closure during the onscrewing rotation to move the projections over the threads of the container finish until the closure threads and container threads are firmly engaged. The top loading requirement adds to the complexity of the capping apparatus for applying tamper-indicating closures.